It's already been announced that Valve will be releasing DLC that lets PC and Mac owners create their own additions to Aperture Science's brain-teasing architecture. Now, a leaked video shows what the Perpetual Testing Initiative looks like in action.

It's a pretty in-depth look at how users will craft, tweak and share the levels. There's no way of knowing how long this video will stay up so watch now if you want to see how Perpetual Testing Initiative works before it comes out later this month.